Document processing devices include printers, copiers, scanners and e-mail gateways. More recently, devices employing two or more of these functions are found in office environments. These devices are referred to as multifunction peripherals (MFPs) or multifunction devices (MFDs). As used herein, MFP means any of the forgoing.
An electrostatic process unit, or EPU, in many printers and multifunction peripherals assists in performing the printing functions. The EPU is also referred to as an electrographic processing unit. The EPU typically comprises a photoconductive drum, and a developer roller, and can include a charge unit, a toner hopper, a semiconductor laser, and developer among other components as would be known in the art. The EPU can be configured as a field replaceable unit or can be part of a self-contained compact cartridge that includes the toner. Using magnetic and electrostatic forces, the developer roller and the photoconductive drum transfer toner from a toner hopper to a sheet of paper where it is fused by heat to the paper. After the photoconductive drum transfers toner to the paper, a cleaner blade in the EPU removes residual toner and paper dust from the photoconductive drum.
However, residual toner and paper dust can be suspended in the air within the EPU, for example within the developer cavity of the EPU. Toner and paper dust, if not entirely removed can leak into other areas of the EPU, particularly when suspended in air. The toner and paper dust can contaminate other EPU components such as the primary charge roller or the corona components, settle on the photoconductive drum and degrade future print jobs, and interfere with the proper operation of an electrostatic process unit.